Add DHCPv6 to documentation

doc/doxygen/lwip.Doxyfile

@@ -2088,6 +2088,7 @@ PREDEFINED             = __DOXYGEN__=1 \
                          LWIP_ICMP=1 \
                          LWIP_RAW=1 \
                          LWIP_DHCP=1 \
+                         LWIP_IPV6_DHCP6=1 \
                          LWIP_UDPLITE=1 \
                          LWIP_UDP=1 \
                          LWIP_IGMP=1 \

src/core/ipv6/dhcp6.c

@@ -1,5 +1,8 @@
 /**
  * @file
+ *
+ * @defgroup dhcp6 DHCPv6
+ * @ingroup ip6
  * DHCPv6 client: IPv6 address autoconfiguration as per
  * RFC 3315 (stateful DHCPv6) and
  * RFC 3736 (stateless DHCPv6).

src/include/lwip/opt.h

@@ -2656,6 +2656,11 @@
  * @}
  */
 
+/**
+ * @defgroup lwip_opts_dhcpv6 DHCPv6
+ * @ingroup lwip_opts_ipv6
+ * @{
+ */
 /**
  * LWIP_IPV6_DHCP6==1: enable DHCPv6 stateful/stateless address autoconfiguration.
  */
@@ -2702,6 +2707,9 @@
 #if !defined LWIP_DHCP6_MAX_DNS_SERVERS || defined __DOXYGEN__
 #define LWIP_DHCP6_MAX_DNS_SERVERS      DNS_MAX_SERVERS
 #endif
+/**
+ * @}
+ */
 
 /*
    ---------------------------------------